The performance of a computer chip (also referred to and known as xe2x80x9cintegrated circuitxe2x80x9d) varies with the voltages, temperatures, and process comers at different points on the computer chip. Accurately knowing these parameters helps chip designers understand and improve chip behavior.
For example, if a voltage supply level for a clock tree is low, the clock tree loses its drive strength, and the integrity of clock signals throughout a computer chip may deteriorate. Thus, it is important to know voltages at particular points on the computer chip to ensure that performance inhibiting behavior is compensated for and/or avoided in chip design.
One approach used by chip designers to monitor voltage on a computer chip involves the allocation of sense points on the computer chip. These sense points are then attached to a trace, or wire, that leads to an exterior area, such as the circuit board, of the computer chip. However, this type of voltage measurement is prone to inaccuracy because the measurement of the voltage on the chip attenuates as the measurement transfers to an area outside the computer chip. Further, such a measurement technique is costly because multiple wires have to be brought out from the computer chip when voltages at multiple locations need to be determined.
Alternatively, chip designers can physically probe different regions within the computer chip. However, this technique is becoming increasingly difficult because empty space within a computer chip is decreasing as modern computer chips become smaller and more device-laden. In cases when physical probing is not feasible, voltage is assumed to be within a certain range.
According to one aspect of the present invention, an on-chip voltage monitor that filters out high-frequency noise in a voltage measurement comprises a divider stage comprising a voltage divider, where the voltage divider comprises a filter formed by a resistor and a capacitor, and where the voltage divider generates a divided voltage signal representing the voltage measurment.
According to another aspect, a method for monitoring a voltage on a section of a computer chip comprises using a voltage divider to divide a voltage on the section, where the voltage divider comprises a resistor and a capacitor, and where the voltage divider generates a divided voltage signal that represents the voltage on the section.
According to another aspect, an integrated circuit having a voltage sensor that measures a voltage at a section of the integrated circuit, the voltage sensor comprises a divider stage disposed on the integrated circuit and having an RC filter configuration that selectively filters noise, where the divider stage divides the voltage to generate a divided voltage signal that represents the voltage at the section.
According to another aspect, a method for observing voltages at multiple sections of an integrated circuit comprises using a voltage sensor to measure a voltage at a section of the integrated circuit, using at least one other voltage sensor to measure at least one other voltage at least one other section of the integrated circuit, and selectively observing the voltage and the at least one other voltage from an observation point, where the observation point is operatively connected to an output of the voltage sensor and an output of the at least one other voltage sensor.
According to another aspect, a computer system comprises an integrated circuit, a voltage monitor disposed on a section of the integrated circuit, at least one other voltage monitor disposed on at least one other section of the integrated circuit, and an observation point operatively connected to an output of the voltage monitor and an output of the at least one other voltage monitor.
Other aspects and advantages of the invention will be apparent from the following description and the appended claims.